cmake: Remove setting CMAKE_FIND_ROOT_PATH_MODE_* variables
cmake: Remove setting CMAKE_FIND_ROOT_PATH_MODE_* variables

These variables affect how CMake locates programs, libraries, include
files, and CMake packages. But the defaults are sufficient for Zephyr.

NEVER: Only host system's root will be searched.
ONLY: Only the paths specified by a variable will be searched. Typically
      these paths point to cross-compilers.

Signed-off-by: Mark Ruvald Pedersen <3c05dc905675c0722f67ee578faf639727313efa@oticon.com>

galak/zephyr,punitvara/zephyr,punitvara/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,ldts/zephyr,zephyrproject-rtos/zephyr,explora26/zephyr,Vudentz/zephyr,galak/zephyr,punitvara/zephyr,Vudentz/zephyr,galak/zephyr,GiulianoFranchetto/zephyr,nashif/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,GiulianoFranchetto/zephyr,ldts/zephyr,galak/zephyr,galak/zephyr,Vudentz/zephyr,finikorg/zephyr,GiulianoFranchetto/zephyr,nashif/zephyr,GiulianoFranchetto/zephyr,finikorg/zephyr,nashif/zephyr,Vudentz/zephyr,explora26/zephyr,zephyrproject-rtos/zephyr,punitvara/zephyr,explora26/zephyr,explora26/zephyr,punitvara/zephyr,nashif/zephyr,finikorg/zephyr,Vudentz/zephyr,GiulianoFranchetto/zephyr,ldts/zephyr,ldts/zephyr,ldts/zephyr,explora26/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr